Copying of graphic originals



April 25, 1967 R. OWEN 3,315,598

COPYING OF GRAPHIC ORIGINALS Filed July 28, 1960 /C/Ci.

MMQLW Yrnographic copy-paper.

United States Patent O 3,315,598 COPYING oF GRAPHIC ORIGINALS RichardOwen, North St. Paul, Minn., assignor to Minne- This invention relatesto the thermographic reproduction of hand-written, typed, printed orother graphic originals. An important aspect of the invention involvesthe preparation of heat-stable, right-reading reproductions employingconventional visibly heat-sensitive opaque ther- The invention isdirected both .to novel processes and to novel compositions and sheetmaterials.

Thermographic processes for the reproduction of differentiallyradiation-absorptive graphic originals, as described, for example, inMiller U.S. Patent No. 2,740,896, involve the application to a visiblyheat-sensitive copysheet of a heat-pattern originating from the briefirradiation of the original with intense radiant energy. Theheat-sensitive layer is preferably held in close contact with theprinted surface, so as to obtain maximum utilization of the heat-patternand to provide maximum sharpness and definition of the image-formingareas. One form of copy-sheet accordingly consists of a visiblyheat-sensitive coating on a thin flexible transparent backing.Irradiation through the copy-sheet, i.e. by front-printing, and with thesensitive coating in contact With the printed surface, -then produces acopy which is viewed through the transparent backing as a right-readingreproduction of the original.

Translucent or opaque backings are available which are adequatelytransmissive of the radiant energy employed and which are easiervtohandle than are the thin transparent webs just described. Copy-sheetsprepared with such backings may similarly be thennographicallyfront-printed7 but the resulting copy is visib'le only from the coatedsurface and therefore as a mirror image of the original. Where possible,such copy-papers are therefore ordinarily used for back-printing, whichhowever is limited to use with thin heat-conductive originals printed onone side only.

The present invention in one aspect provides for the preparation, bythermographic front-printing techniques, of right-reading reproductionson opaque, sturdy, easily handled backings.

The visibly heat-sensitive copy-sheets employed in thermographicreproduction remain visibly heat-sensitive in background areas.Subsequent application of heat may therefore distort or obliterate thecopy. The present invention makes possible the stabilization of theinitial reproduction against subsequent heating, and provides for.

a permanent copy.

The invention also makes possible the reproduction of graphic originalsby lithographie printing techniques using a lithographie master preparedby a process involving thermographic duplication. These yand otherobjects and advantages of the invention are attained by means of animage transfer procedure as hereinafter described and particularly inconnection with the accompanying drawings;

-FIGURE 1 illustrates conventional thermocopying techn1 ue:

IFIGURES 2 and 3 illustrate a thermocopying technique in accordance withone embodiment of the present invention;

FIGURES 4 and 5 illustrate a thermocopying technique in accordance witha second embodiment of the present 70 invention wherein the transfersheet may be used as a lithographie master; and

3,3 15,5 98"y Patented Apr. 25, 1967 ICC FIGURE 6 illustrates athermocopying technique in accordance with a third embodiment of thepresent invention.

FIGURE 1 illustrates conventional thermocopying technique, for exampleas described in the Miller patent above referred to, in which a graphicoriginal 10 is irradiate with intense radiation from a source 11 througha visibly heat-sensitive copy-sheet 12 having a heat-sensitive layer 13on a visibly transparent, radiation-transmissive backing 14. Theradiation is preferentially absorbed in the inked areas 15, providing alocalized heating eiect which causes a visible change in correspondingareas 16 of the heat-sensitive layer 13 to produce a right-readingreproduction of the graphic original as viewed through the backing 14.

In FIGURE 2, in accordance with the principles of the present invention,the thus treated copy-sheet 12 is next pressed against aheat-activatible sheet 17, having a normally non-tacky, heat-activatibleadhesive layer 18 0n a backing 19. Heat and pressure are convenientlyprovided by means of rollers 20, 21 or by other means as desired. Theadhesive layer 1S is activated and is adhered to the sensitive coating13. The composite is next cooled to room temperature, and the lbacking14 is stirpped away from the sensitive layer 13 which remains adherentlybonded to the transfer sheet 17, as shown in FIG- URE 3. As viewed fromthe exposed surface, the sensitive layer 13 provides a direct-readingreproduction of the printed original 10.

When the copy-image is itself radiation-absorptive, a source 11 ofradiant energy may alternatively be employed in providing a localizedheating effect at the image areas. The adhesive layer 18 is therebylocally activated at those areas in contact with the image areas of thesensitive layer 13 in the composite of FIGURE 2. Pressure maysimultaneously lbe applied by any convenient means, for example througha transparent cover plate or lm, or by holding the composite undertension over a convex supporting surface. The image areas are therebyselectively adhered to the adhesive layer. Removal of the ybacking 14 bystripping then removes the unchanged portions `22 of the sensitive layer'13, leaving the imageforming areas 16 adherently retained by theadhesive layer 18 of the receptor sheet 17, as illustrated in FIGURE 4.Such a copy is no longer visibly changed on further heating.

In those forms of heat-sensitive copy-paper in which the 'heat-imagesformed are not lpreferentially radiationabsorptive, the energy source`11 of FIGURE 1 may still be employed, in conjunction with suitablepressure-applying means, in activating the adhesive layer of the sheet17 of FIGURE 2. For this purpose, the sheet 17 is itself maderadiation-absorptive, e.g. 'by employing a suitably colored backing l19or by incorporating small amounts of carbon black or the like in theadhesive layer 18. Since irradiation then causes activation of theentire adhesive layer, the resulting separation occurs as illustrated inFIGURE 3.

In `some instances the image-'carrying transfer sheet of FIGURE 4 maysubsequently be employed as a -master sheet in the lithographieduplication of the image. As illustrated in 'FIGURE 5 there is rstapplied a coating of a fountain solution 423 which is preferentiallyaccepted -by the exposed surfaces of the heat activatible adhesivecoating 18, followed by application of a coating of an ink composition24 which is preferentially accepted by the exposed surfaces of the imageareas 16. The ink is then transferred to a receptor sheet as inconventional lithographie duplicating. A negative print is producedwhere the preferential receptivity of the image and Ibackground areas isreversed.

I at room temperature.

1 Twenty parts by weight Example 1 A heat-sensitive copy-sheet is firstprepared by applying .a thin uniform layer of a iuid mixture of reagentsand binder to thin transparent paper (Ecusta -condenser tissue) by knifecoating at -an orifice 4of 3 mils, and drying The coating mixturecontains the following in parts by weight as indicated:

Mixture -of equal molar parts of silver behenate and behenic aciddispersed in ethyl acetate at con- The white copy-sheet is placed over agraphic Voriginal printed in black ink onV White paper, and thecomposite is momentarily exposed to intense radiation from anincandescent filament in the thermographic copying process hereinbeforenoted, producing a copy of the original image in brownish black denseletters on a white background. The exposure is accomplished in athermocopying machine as described in Kuhrmeyer et al. Patent No.v2,891,165. i

A heat-activatible receptor sheet is prepared by applying a thin uniformlayer of amixture of 33 parts by weight of polyvinyl butyral resin, 33parts of waxy hydrogenated castor oil, 22 partsV of Vliquid chlorinateddiphenyl, and 1l Yparts of Z-biphenyly-l diphenylphosphate, to 45'poundbook paper.- The coating is applied at a rate of 18 grams per squarefoot and at an elevated temperature at which the mixture is uid. Thecoating is VVnon-tacky at norma-l room temperatures but softens andbecomes sticky at temperatures o-f the order of 65"Y C. The copy isplaced with the imaged coated surface in Ycontact with the coatedsurface of the receptor sheetrand the composite is again passed through'the thermocopying machine and briefly intensely irradiated, with thecopy toward the source of radiation. The exposure is controlled toprovide suicient heating at the image areas to soften and activate theadhesive coating while avoiding any-'visible change at the backgroundareas. The

Parts centration 10 Y Ten-percent solution of polystyrene reisn 1nacetone,

containing added 2% of protocatechuic acid 30 composite Vis then cooledand the paper backing of the Y copy-sheet isV stripped away, taking withit the unchanged and still heat-sensitive coating at the backgroundareas. The visibly darkened -image areas of theheat-sensitive coatingremain adherently bonded to thereceptor sheet; w The heat-sensitivebackground areasof the copysheet may Vnow be-visibly changed to abrown-black color by heating, e.g. on a heated plate or inran oven, toproduce vaV negative transparencyof the graphic original.

Example 2 Y 'The heat-sensitive coating of Example 1Y is applied to mapoverlay tracing paper 'in-place of the condenser tissue there employed.A thermographic copy of a graphic original is prepared and the copyplaced in contact with the adhesive receptor sheet of Example 1. The

composite is subjected toheat and pressure by pressing Vwith a atironata temperature just below that required to cause .a visible change inthebackground areas of the heat-sensitive.copy-sheet. After cooling,the'tracing paper is stripped away.V The entire heat-sensitive layer isfound to remain adherently-bonded to the receptor sheet;

Y i Example 3 Y. In this example anormally non-tacky heat-activatibleadhesive composition initially included Vin Ythe composition of thevisibly heat-sensitive Vcoating Yis transferred to an uncoated paperbacking simultaneously with the image-'forming components. v

of mercurio behenate isY rst dispersed in a'mixture of 48 partscommercialheptane and 32 parts acetone by milling on a ball mill.'Separately, one-half part of s-diphenyl carbazide is dissolved in amixture of 45 parts toluene and 45 parts acetone.

, ferentilally radiation-absorptive graphic original, coma visiblereproduction of the'printed image areas in-.the 1 heat-sensitivecoating. The copy is then placed with the imaged surface against a roughsurface bond paper and the composite againirradiated. The imageportionsrof the copy are selectively softened and adhered lto the bondpaper; on stripping the two sheets apart, a distinct copy of the imageremains on the paper, althoughY a majorproportion of the image materialremains on the copysheet. Repeating the same procedure'with furthersheetsy of the bond paper produces a numberrof additional copies Vbeforethe image material is depleted, as many 'paseiglit copies having therebybeen prepared. The transferV step isillustratedpreviously imagedportions 16 of the heat-sensitive-and heat-activatible layer 13 areselectivelyV softened and adhered to the untreated paper 19., andportions thereof' remain on the paper-when the copy-sheet 12'. isstripped away. Y Multiple copies have'somewhat analogously been pre-:pared by the methods described in Examplesl V1 and-2f,V where thepolystyrene resin'binderV there employed was replacedrby Va somewhatsofter resinoiis material. Y

The materials transferred at` lthe image areas in Example 3are'organophilic in nature, whereas the bond paperY receptor sheet ishydrophilic. Under these condif.

tions it becomes possible tofprepare further `copies'fby lithographiereproduction.- The background areas are' first coated Vwith an aqueousfountain solution, such as a -V dilute'solution of arabic in'water,which isY selectivey 1 ly retained by these lhydrophilic surfaces. YOil-based ink is next applied and is selectively retained by theoleophilric surfaces of the image areas.V The ink isthen'r'transferr'edV under pressure topa paper receptor, either directlyor by Y means of an intermediate blanket roller. YSuitable coated orstrengthened hydrophilic sheet materials may replace the bond paperWhere longer runs are desired.

-Lithographie reproduction may also beV carried outV Y Y.usingheat-activatible adhesiveV receptor sheets as the f lithographie plates,particularly by incorporating inthe adhesive layer a hydrophiliccomponent suchgas a water-V` Y soluble gum or a'hydrophilic inorganicfiller-'such as silica j gel, or by the use of anV ink-repellentheat-activatible ad f hesive such as a waxy water-soluble polyethyleneglycol.

V.Systems in which Ythe'adhesive-coating is oleophilicV and thetransferred heat-image material'is hydrophilic are a-lso. i

contemplated, the Vcopy resulting Vin Vthis case being a negative ratherthan Y based inks. ,Y Y

What is-claiined is as follows:Y v Y .1. The method of preparing areproduction ofr'ardifprising: subjecting a heat-sensitive copy-sheet'tolocalizedr heating at'areas corresponding'to'image-forming areas of saidoriginal by a thermographic process to provideY a visible. reproductionof said image-forming areas, saidVV i copy-sheet includingY a visiblyheat-sensitive coating-on a5 flexible carrier; placing said copy-sheetwith its coated surface in pressure-contact with the heat-activatiblesur-V face of a normally non-tackyAadhesivereceptorsheet and heating atleast the portions nof said-heat-activatible .sur-'gf face correspondingto saidv image-forming areas toi pro- Y vide adherent bondin'g'betweensaid coating-and said's'uri face while avoiding visible change atbackground Vareas' j Y Y of said .copy-sheet; and removing said carrierbyV stripping Y 2. The method of preparing a reproductionof a dif-Q Y.

' FIGURE 6.5 Yuit.V

a positive'copy when usingV oilferentially radiation-absorptive graphicoriginal, comprising: subjecting a heat-sensitive copy-sheet tolocalized heating by a thermographic process at areas corresponding toimage-forming areas of said original to provide a visible reproductionof said image-forming areas, said copy-sheet including aradiation-transmissive flexible carrier and a heat-sensitive coatingwhich is permanently visibly changed and rendered stronglyradiation-absorptive when heated in said thermographic process; placingsaid copy-sheet with its coated surface in pressure-contact with theheat-activatible surface of a normally non-tacky adhesive receptor sheetand briey strongly irradiating the heat-sensitive coating to causeactivation and bonding of said adhesive at image areas while avoidingvisible change at background areas of said copy-sheet; and removing saidflexible carrier by stripping.

3. The method of making a lithographie master printing plate formultiple reproduction of a graphic original, comprising: subjecting a-heat-sensitive copy-sheet to localized heating by a thermographicprocess at areas corresponding to image-forming areas of said originalto provide on said copy-sheet a reproduction of said imageforming areas,said copy-sheet including a exible carrier and a heat-sensitive coatingthereon which is visibly changed and rendered' stronglyradiation-absorptive when heated in said thermographic process; placingsaid copysheet with its coated surface in pressure-contact with theheat-activatible surface of a normally non-tacky adhesive receptor sheetand briefly strongly irradiating the heatsensitive coating to causeactivation and bonding of said adhesive at image areas while avoidingvisible change at background areas of said copy-sheet; and removing saidflexible carrier, together with background areas of said heat-sensitivecoating remaining attached thereto, by stripping, whereby to exposeareas of said adhesive coating corresponding to said background areas;one of said adhesive coating and said heat-sensitive coating beinghydrophilic, the other being organophilic.

4. The method of preparing -a reproduction of a differentiallyradiation-absorptive graphic original, comprising; subjecting aheat-sensitive copy-sheet to localized heating by a thermographicprocess at areas corresponding to image-forming areas of said originalto provide a visible reproduction of said image-forming areas, saidcopy-sheet consisting essentially of a flexible carrier and aheat-sensitive coating thereon which is permanently visibly changed to astrongly radiation-absorptive colored state when heated in saidthermographic process and which includes a heat-activatible normallynon-tacky soft polymeric binder material; placing said copy-sheet withits coated surface in pressure-contact with a receptor sheet; brieystrongly irradiating the image lheatsensitive coating to causeactivation and bonding of said binder material at colored image areas tosaid receptor sheet while avoiding visible change at background areas ofsaid copy-sheet; and separating said receptor sheet, together withadherently bonded portions of said copysheet coating retained thereon,by stripping from said copy-sheet.

5. The method of copying comprising: briefly exposing to intense radiantenergy a differentially radiationabsorptive graphic original while inheat-conductive contact with a copy-sheet having a visiblyheat-sensitive coating on a exible carrier, to provide a correspondingdifferential heat pattern sufficient to form on said copy-sheet avisible copy of said original; placing said copy-sheet with the coatedsurface in contact with a receptor sheet and heating the composite atleast at image areas of said copy to an adhesion-inducing temperature;and stripping from said recept-or any portion of said copy-sheet notadherently bonded thereto; at least one of said copysheet and saidreceptor sheet having a thermoadhesive normally non-tacky surfacecoating which is adhesive when heated to said temperature.

6. The method of copying comprising: -briediy subjecting adifferentially radiation-absorptive graphic original to intenseradiation from an incandescent filament while the original is inheat-conductive contact with a copysheet product having a heat-sensitivecoating, to create at the image areas of said original la heat patternwhich is conducted to `a copy-sheet and effects a permanent change insaid coating at areas corresponding to said image areas; placing thecopy-sheet with its said coating in pressure-conatct with the surface ofa receptor sheet, at least one of said coating land said surfacecomprising a heat-activatible normally nontacky adhesive bondingmaterial; heating the composite at least at image areas of said copy toan adhesion-inducing temperature for said bonding material, to effectadhesion between said coating and said surface at the heated areas; andseparating the copy-sheet and receptor sheet to provide on said receptora copy of said graphic original.

References Cited by the Examiner UNTTED STATES PATENTS 2,503,758 4/1950Murray lOl-426 X 2,663,654 12/ 1953 Miller et al.

2,721,821 10/-1955 Hoover 156-230 2,740,896 4/ 1956 Miller 250-65J12,808,777 10/ 1957 Roshkind Z50-65.1 X 2,910,377 10/ 1959 Owen 250-65.1X 2,939,009 5/ 1960 Tien 101-426 X 2,954,311 9/ 1960 Vander Weel lOl-149.4 X y3,060,023 10/-1962 Burg et al -101-149.4 X 3,063,863 lil/1962Holland et al. Z-65.1 X 3,109,748 11/ 1963 Newman Z50-65.1 X 3,121,6502/'1964 Meissner lOl-426 X '3,122,997 3/ 1964 Raczynski et al. Z50-'65:1X 3,129,661 4/1964 Newman Z50-65.1 3,147,377 9/1964 INewman Z50-65.1

FOREIGN PATENTS 722,023 1/ 1955 Great Britain.

ROBERT E. RULFREY, Primary Examiner. DAVID KLEIN, Examiner. B. A.LEIGHEY, lE. T. WRIGHT, Assistant Examiners.

1. THE METHOD OF PREPARING A REPRODUCTION OF A DIFFERENTIALLYRADIATION-ABSORPTIVE GRAPHIC ORIGINAL, COMPRISING: SUBJECTING AHEAT-SENSITIVE COPY-SHEET TO LOCALIZED HEATING AT AREAS CORRESPONDING TOIMAGE-FORMING AREAS OF SAID ORIGINAL BY A THERMOGRAPHIC PROCESS TOPROVIDE A VISIBLE REPRODUCTION OF SAID IMAGE-FORMING AREAS, SAIDCOPY-SHEET INCLUDING A VISIBLY HEAT-SENSITIVE COATING ON A FLEXIBLECARRIER; PLACING SAID COPY-SHEET WITH ITS COATED SURFACE INPRESSURE-CONTACT WITH THE HEAT-ACTIVATIBLE SURFACE OF A NORMALLYNON-TACKY ADHESIVE RECEPTOR SHEET AND HEATING AT LEAST THE PORTIONS OFSAID HEAT-ACTIVATIBLE SUR-